JPH09272689A - Crane controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically stop driving at the same time of landing of a load by stopping the driving of a motor, when a load current of a variable speed gear for the crane motor is detected and the load current is lower than a prescribed current reference value. SOLUTION: A current detector 1 detects a load current I1 of an inverter and sends a signal to a current comparator 2. The current comparator 2 compares the load current I1 to a prescribed current reference value Is1, and when the load current I1 < the current reference value Is1, a reset signal of speed instruction N is sent to a speed instruction device 3, and when the load current I1 > the current reference value Is1, a continuation signal is sent to the speed instruction device 3. When the speed instruction device 3 receives the reset signal from the current comparator 2, it stop the driving of the crane. When the speed instruction device 3 receives the operation continuation signal, the driving is continued without resetting the speed instruction. When a load suspended from the crane is landed and the load current I1 < the current reference value Is1, the driving of the crane is automatically stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crane control device, and more particularly to a crane control device that stops operation when a load attached to a crane lands on a floor.

[0002]

2. Description of the Related Art For example, when a load is transferred using a crane controlled by a variable speed device such as an inverter, the load that has been lifted up to that point is naturally landed at the end of transfer. The judgment was made by human eyes. That is, an operator who has a controller that sends an operation / stop command to an inverter visually operates the crane while checking the surrounding conditions and the state of the load to land the load on the floor.

[0003]

As long as the application can be visually confirmed as described above, it is not possible to visually confirm whether or not the luggage has landed, such as when the luggage is unloaded under the sea. There is also. In such a case, the crane will continue to operate for a while after landing, consuming power wastefully,
Since the wire on which the luggage is attached also sags, there is a problem that the wire is entangled or the wire comes off the luggage. An object of the present invention is to provide a crane control device capable of automatically stopping the operation at the same time when the luggage is landed in order to solve the problems in the conventional art.

[0004]

In order to achieve the above object, the present invention detects the load current of a variable speed device for a crane motor, and when the load current falls below a predetermined current reference value, It is configured as a crane controller that stops the operation of the electric motor. Further, it is a crane controller for setting the speed command of the variable speed device to 0 and stopping the operation of the electric motor when the load current becomes lower than the current reference value. Further, the variable speed device is a crane controller which is an inverter.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
It should be noted that the following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. FIG. 1 is a block diagram showing a schematic configuration of the crane controller 0 according to the embodiment of the present invention. As shown in FIG. 1, a crane controller 0 according to an embodiment of the present invention is a variable speed device that is composed of a current detector 1, a current comparator 2 and a speed command device 3 and controls the electric motor M. The operation is stopped by setting the speed command of the inverter 4 to zero.

Details of the crane controller 0 will be described below. In FIG. 1, the current detector 1 detects the load current I _{L of the} inverter and sends a signal to the current comparator 2. The current comparator 2 compares the detected load current I _L with a predetermined current reference value I _st, and if the load current I _L becomes smaller than the current reference value I _st , the speed commander 3 sends a speed command N. A reset signal (for example, 0) for resetting is sent, and if the load current I _L is the current reference value I _st or more, a continuous operation signal (for example, 1) indicating continuous operation is sent to the speed command device 3. When the speed commander 3 receives the reset signal from the current comparator 2, the speed commander 3 multiplies the speed command N by 0, updates the speed command to 0, and stops the operation of the crane. Speed commander 3
When the above-mentioned operation continuation signal is received, the speed command N is multiplied by 1, and the operation is continued without resetting the speed command. When the load hung on the crane lands on the floor, the load current I _L decreases. When the load current I _L becomes smaller than the current reference value I _st , the operation of the crane automatically stops.

[0007]

[Embodiment] In the crane control device according to the embodiment of the present invention described above, circuits such as the current comparator 2 and the speed commander 3 are used. The current reference value may be easily changed by software by inputting it to an arithmetic means such as a microcomputer. Such a crane control device is also an example of the crane control device in the present invention.

Since the present invention is configured as described above, it is possible to stop the operation of the crane at the same time when the load is landed and prevent the wire attached to the load from slackening.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a crane controller 0 according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... Current detector 2 ... Current comparator 3 ... Speed command device 4 ... Inverter M ... Motor

Claims (3)

[Claims] 1. A crane control device for detecting a load current of a variable speed device for a crane electric motor and stopping the operation of the electric motor when the load current falls below a predetermined current reference value. 2. The crane control device according to claim 1, wherein when the load current is lower than the current reference value, the speed command of the variable speed device is set to 0 and the operation of the electric motor is stopped. 3. The crane controller according to claim 2, wherein the variable speed device is an inverter.